1. Field of the Invention
The present invention generally relates to a microfluid handling device having a flow passage capable of allowing a fluid to run therein due to capillarity. More specifically, the invention relates to a microfluid handling device which is used as a micro chip or the like in a technical field called integrated chemistry and which is used for moving and/or mixing plural kinds of very small amounts of liquid samples or used as a POC (point of care) inspecting device.
2. Description of the Prior Art
In recent years, there is known a technique called integrated chemistry for forming a fine groove having a width and depth of about one to thousand micrometers in a micro chip of a glass or plastic, to use the fine groove as a liquid passage, reaction vessel or separation/purification detecting vessel, to integrate a complicated chemical system into the micro chip. According to such integrated chemistry, a micro chip (Lab-on-a-chip) having a fine groove used in various tests is called μ-TAS (Total Analytical System) if the use of the micro chip is limited to analytical chemistry, and the micro chip is called micro reactor if the use of the micro chip is limited to a reaction. When various tests, such as analyses, are carried out, integrated chemistry has advantages that the time to transport diffuse molecules is short due to small space and that the heat capacity of a liquid phase is very small. Therefore, integrated chemistry is noticed in the technical field wherein a micro space is intended to be utilized for carrying out analysis and chemical synthesis. Furthermore, the term “test” means to carry out any one or combination of operations and means, such as analysis, measurement, synthesis, decomposition, mixing, molecular transportation, solvent extraction, solid phase extraction, phase separation, phase combination, molecule acquisition, culture, heating and cooling.
In such integrated chemistry, it is required to open and close a fine liquid passage, which has a width and height of about one to thousand micrometers and which is formed in a glass or plastic chip, to allow a sample to move in the fine liquid passage. Thus, there have been proposed various valve structures for opening and closing a fine liquid passage.
For example, in a technique disclosed in Japanese Patent Laid-Open No. 2002-36196, a movable film of a photoresponsive material arranged in a branch connection or the like of a liquid passage is irradiated with laser beams to be deformed so as to control the flow of a liquid in the liquid passage. In a technique disclosed in Japanese Patent Laid-Open No. 2002-66399, a gel chamber formed in the middle of a capillary tube-like passage is filled with a temperature sensitive gel which is heated to be expanded to protrude into the capillary tube-like passage to change the cross-sectional area of the passage. In a technique disclosed in Japanese Patent Laid-Open No. 2002-282682, a solenoid valve arranged in the middle of a fine liquid passage is open and closed to control the flow of a very small amount of sample.
However, in the above described conventional techniques disclosed in Japanese Patent Laid-Open Nos. 2002-36196, 2002-66399 and 2002-282682, a valve mechanism is provided in the middle of a liquid passage having a vary small cross-sectional area, and it is difficult to work such a valve mechanism, so that there is a problem in that a plate (e.g., a micro chip) having such a valve mechanism is very expensive.